Flavor sheet for smoking article

ABSTRACT

Flavor-bearing sheets for the controlled delivery of volatile flavorants in a smoking article are disclosed. The flavor-bearing sheets comprise a non-volatile vitreous matrix of a film-forming coagulating material having one or more volatile flavorants dispersed therein.

This application claims priority under 35 USC 119(e)(1) of U.S.Provisional Patent Application Ser. No. 60/690,759, filed Jun. 14, 2005,the entirety of which is incorporated herein by reference as if fullyset forth herein.

FIELD OF INVENTION

The present invention relates generally to compositions for deliveringflavor to smoking articles. More specifically, the invention relates toflavor-generating compositions which reduce migration of volatile flavorconstituents such as menthol from the tobacco column of a cigarette.

BACKGROUND OF THE INVENTION

The popularity of mentholated cigarettes has grown rapidly since theirintroduction in the United States in the 1920's. Today, mentholatedcigarettes account for approximately one quarter of all cigarette salesin the United States.

Conventionally, menthol has been incorporated into cut tobacco filler inmentholated cigarettes. Because menthol is a crystalline solid at roomtemperature, it is usually applied by spraying the filler with anethanolic solution of menthol. Tobacco filler treated in this mannertypically contains between 0.3 and 1.3% by weight menthol.

However, the amount of menthol ultimately delivered to the smoker hastraditionally proven difficult to control. There are several factorsthat affect the menthol delivery of a cigarette. For example, much ofthe menthol in conventional mentholated cigarettes does not enter themainstream smoke when the cigarette is smoked and is consequently notdelivered to the smoker. Approximately, 75% of the menthol is lost tothe sidestream smoke.

Loss of menthol on storage of mentholated cigarettes further reduces theamount of menthol ultimately delivered to the smoker. In fact, thementhol delivery of conventional mentholated cigarettes can be reducedby 57% after six months of storage in sealed cigarettes packages.Temperature and humidity conditions under which cigarettes are storedexert a substantial impact on menthol loss and consequently, significantdifferences in menthol delivery have been observed for the same brand ofcigarettes in different regional markets.

The loss of menthol upon storage is due to the volatile nature ofmenthol which freely sublimes at room temperature. If menthol isinitially located in the tobacco filler of a cigarette, substantialquantities will migrate to the packaging and atmosphere, during storage.

In addition, if the cigarette includes a filter, the menthol will alsotend to migrate from the tobacco filler to the filter. The degree ofmigration of menthol to the filter depends on the characteristics of thecomponents comprising the filter. Conventional cigarette filters areformed from fibrous material, such as cellulose acetate, that has beengathered into a plug (i.e., a filter “tow”). The tow is held together bya plasticizer, commonly triacetin, which has been applied to the fibers.Studies have demonstrated that up to 35% of the menthol initially addedto the tobacco filler migrates to the filter tow within a few weeks ofstorage. Menthol may be associated strongly with the plasticizer andtherefore be unavailable for delivery to the smoker.

Conventional cellulose acetate tow filters are designed to removeparticulate matter from mainstream smoke but are ineffective to removeor reduce gas phase constituents. The gas phase of mainstream cigarettesmoke contains certain components alleged to be harmful to a smoker,including certain aldehydes and olefinic constituents. Filters have beendesigned for the removal of gas-phase constituents along withparticulates. Such filters typically incorporate an adsorbent materialsuch as activated carbon (also known as “carbon,” “charcoal,” or“activated charcoal”) in a section of the filter. High surface areaactivated carbon is recognized as an effective adsorbent for removinggas phase components from mainstream smoke.

However, the use of activated carbon filters in mentholated cigaretteshas met with only limited success to date. This is due largely to thefact that activated carbon is a very effective adsorbent of menthol.Thus, the greater part of menthol added to tobacco filler isirreversibly adsorbed by the activated carbon during storage and istherefore not available to be delivered to the smoker. For that reason,mentholated cigarettes having adsorbent filters traditionally haverequired larger amounts of menthol to be added to the tobacco fillerduring manufacture to offset adsorption by the carbon.

In light of the foregoing considerations, it is therefore an object ofthe present invention to provide cigarettes flavored with volatileflavorants, such as menthol, which limit the dissipation of volatileflavorant from the cigarette during storage.

It is another object of the invention to provide volatile flavorants,such as menthol, in a form which is compatible for use withadsorbent-bearing cigarette filters.

SUMMARY OF THE INVENTION

In accordance with the foregoing objectives and others, the presentinvention provides compositions in the form of flavor-bearing sheets forthe controlled delivery of volatile flavorants, such as menthol, to asmoker during smoking while reducing the migration of flavorantthroughout the cigarette and packaging during storage.

In one aspect of the invention, a flavor-bearing sheet for thecontrolled delivery of volatile flavorants in a smoking article isprovided. The flavor-bearing sheet comprises a non-volatile vitreousmatrix having a volatile flavorant, such as menthol, dispersed therein.The non-volatile matrix is provided by film-forming coagulatingmaterials such as, for example, polyols, polymeric ethers, polymericesters, natural polymers and derivatives thereof, and combinationsthereof. The film-forming coagulating materials comprise between about15 to about 80% by weight of the flavor-bearing sheet and the volatileflavorant comprises between about 20 to about 75% by weight of theflavor-bearing sheet. The flavor-bearing sheets of the inventionfunction to inhibit migration of volatile flavorants through physicalentrapment of the flavorant in the low-vapor pressure matrix. Theflavor-bearing sheets are dispersed in the tobacco column of a cigaretteand release flavor into mainstream smoke upon combustion.

The flavor-bearing sheets of the present invention are particularlyuseful for cigarettes having filters which incorporate gas phaseadsorbents, such as activated carbon, because the volatile flavorant isisolated from the adsorbent until the cigarette is smoked. In accordancewith this aspect of the invention, a cigarette is provided comprising anadsorbent-bearing filter and a tobacco column abutting the filter,wherein the tobacco column includes a smokable material comprisingshredded tobacco filler in admixture with a plurality of flavor-bearingsheets. In one implementation, the cigarettes include a so-called“plug-space-plug” filter having an adsorbent, such as granular activatedcarbon, disposed in a cavity formed between two fibrous filtercomponents. Alternatively, the cigarettes may include so-called“dalmation” filter components wherein adsorbents such as activatedcarbon are dispersed in a fibrous tow material. The cigarettes of thepresent invention exhibit greatly diminished menthol loss on storage ascompared to conventionally mentholated cigarettes. For example, themainstream smoke menthol delivery of the cigarettes havingflavor-bearing sheets according to the present invention may be greaterthan about 70% of its initial value after storage for about 25 weeks ina sealed cigarette package.

These and other aspects of the present invention will become apparent tothose skilled in the art after a reading of the following detaileddescription of the invention, including the illustrative embodiments,examples and figures.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings are for the purpose of illustrating the invention and arenot intended to be limiting.

FIG. 1 is a graph comparing the weight loss of menthol from shreddedflavor-bearing sheets of the present invention prepared according toExample 1 and conventional mentholated tobacco.

FIG. 2 is a graph comparing the weight loss of menthol from shreddedflavor-bearing sheets of the present invention prepared according toExamples 5 and 6 and conventional mentholated tobacco.

FIG. 3 is a graph comparing the menthol content of shreddedflavor-bearing sheets dried using an infrared lamp and shreddedflavor-bearing sheets dried ambiently.

FIG. 4 is a graph illustrating the mainstream smoke menthol levels forcigarettes having shredded flavor-bearing sheets prepared according toExample 1.

FIG. 5 is a graph comparing the mainstream smoke menthol levels forcigarettes having shredded flavor-bearing sheets prepared according toExample 1 and conventional mentholated cigarettes.

FIG. 6 is a graph of the mainstream smoke menthol content for cigaretteshaving shredded flavor-bearing sheets of the present invention preparedaccording to Example 11 after the cigarettes have been removed fromsealed packages at weekly intervals of time.

FIG. 7 is a graph of the taste ratings of cigarettes having shreddedflavor-bearing sheets of the present invention prepared according toExample 11 after the cigarettes have been removed from sealed packagesat monthly intervals of time.

DETAILED DESCRIPTION

The present invention is founded on the discovery that migration ofmenthol and other volatile flavorants in a cigarette may be retarded byphysically entrapping them in a non-volatile matrix which is capable ofreleasing the flavorant in response to heat or moisture generated uponcombustion of the cigarette. The matrix takes the form of a vitreous(i.e., glassy) sheet which may be shredded and mixed with tobacco in thecolumn of cigarette.

a. Flavor Sheets

The non-volatile matrix is provided by a film-forming coagulatingmaterial. While there is essentially no limitation on the selection ofthe film-forming coagulating material, it should be a material which iscompatible with a smoking article, i.e., one which does not yieldharmful products of combustion. Suitable materials include withoutlimitation, polyols, polymeric ethers, polymeric esters, naturalpolymers and derivatives thereof, and combinations thereof.

Useful polyols are exemplified by sugars and sugar alcohols, including,but not limited to, erythritol, glycerol, isomalt, mannitol, sorbitol,xylitol, maltitol, lactitol, hydrogenated starch hydrolysate, dextrose,glucose, fructose, sucrose, maltose, galactose, lactose, inositol, cornsyrup and the like. Glucamine, glucose glutamate, glucuronic acid,glycerin, 1,2,6-hexanetriol, hydroxystearyl methylglucamine, malitol,methyl gluceth-10, methyl gluceth-20, methyl glucose dioleate, methylglucose sesquicaprylate/sesquicaprate, methyl glucose sesquicocoate,methyl glucose sesquiisostearate, methyl glucose sesquilaurate, methylglucose sesquistearate, phytantriol, riboflavin, sorbeth-6, sorbeth-20,sorbeth-30, sorbeth-40, and thioglycerin are also non-limiting examplesof polyols which may be useful in the practice of the invention.

Polymeric ethers include, for example, the reaction products of alkyleneoxides, represented by the general formula:

wherein R and R₁ are independently selected from hydrido and C₁-C₂₀branched or straight chain alkyl and n is an integer greater than 2.Preferred polymeric ethers are polyalkylene glycols, such aspolyethylene glycol (PEG) and polypropylene glycol (PPG). Copolymers ofpolymeric ethers, including for example, PEG/PPG copolymers, are alsocontemplated to be useful. Polymeric ethers also include alkoxylatedalcohols such as polyoxyl 20 cetostearyl ether (Atlas G-3713), poloxyl 2cetyl ether (ceteth-2), poloxyl 10 cetyl ether (ceteth-10), poloxyl 20cetyl ether (ceteth-20), poloxyl 4 lauryl cetyl ether (laureth-4),poloxyl 23 lauryl cetyl ether (laureth-23), poloxyl 2 oleyl ether(oleth-2), poloxyl 10 oleyl ether (oleth-10), poloxyl 20 oleyl ether(oleth-20), poloxyl 2 stearyl ether (steareth-2), poloxyl 10 stearylether (steareth-10), poloxyl 20 stearyl ether (steareth-20) and poloxyl100 stearyl ether (steareth-100), and the like.

Suitable polymeric esters include without limitation those representedby the general formula:

wherein each occurrence of R* is independently selected from hydrido andC₁-C₂₀ branched or straight chain alkyl; m is an integer from 0 to 5;and n is an integer greater than 2. Such polymeric esters include thepolyhydroxyalkanoates poly-3-hydroxybutyrate (PHB),poly(3-hydroxypropionate), poly(3-hydroxybutyrate),poly(3-hydroxyvalerate), poly(3-hydroxyhectanoate),poly(3-hydroxyoctanoate), poly(3-hydroxydodecanoate),poly(4-hydroxybutyrate), poly(5-hydroxyvalerate), and the like. Otherinteresting polymeric esters include polylactic acid (PLA),polyglycolide, and polycaprolactone (PCL).

Suitable natural polymers or natural polymer derivatives include withoutlimitation starch and starch derivatives, including maltodextrin;cellulose and cellulose derivatives, including for example, methylcellulose, ethyl cellulose, cellulose acetate, cellulose propionate,cellulose butyrate, cellulose acetate-butyrate, hydroxyethyl cellulose,hydroxypropyl cellulose, carboxymethyl cellulose, carboxyethylcellulose, hydroxypropyl carboxymethyl cellulose, hydroxypropyl methylcarboxyethyl cellulose, hydroxypropyl carboxypropyl cellulose,hydroxybutyl carboxymethyl cellulose, and alkali metal salts of thesecarboxyalkyl celluloses; alginate and alginate derivatives such asalginic acid, sodium alginate, potassium alginate, ammonium alginate,magnesium alginate, calcium alginate, sodium triethanolamine alginate,and propylene glycol alginate (hydroxypropyl alginate); and othervegetable gums including but not limited to carrageenan, dextran,furcellaran, pectin, gelatin, gum agar, locust bean gum, gum ghatti,guar gum, gum tragacanth, acacia, gum arabic, xanthan gum, karaya gum,and tara gum.

The film-forming coagulating materials of the present invention stand incontrast to the heat-irreversible coagulating (i.e., gelling) glucansdisclosed in U.S. Pat. Nos. 4,109,663, 5,778,899, 6,109,272, and6,499,490, the disclosures of which are hereby incorporated by referenceherein. Such heat-irreversible coagulating or gelling glucans aretypically 1,3-β-glucans, as exemplified by curdlan. Unlike theheat-irreversible coagulating glucans, it is not necessary to apply heatto the cast emulsion in order to gel the matrix materials of the presentinvention. Second, in the practice of the present invention, it isdesirable for the flavor-bearing sheets to release flavorant into themainstream smoke prior to combustion of the flavor-bearing sheet inorder to minimize loss of menthol to side stream smoke. This may beaccomplished by any non-combustion release mechanism, whereby hot gasesgenerated by the advancing fire cone induce decomposition of the flavorsheet. Without wishing to be bound by any theory, it is believed thatwater vapor produced by combustion of tobacco dissolves or decomposesthe flavor-bearing sheets, thereby liberating the entrapped flavorant.This mechanism is not possible with the heat-irreversible coagulatingglucans described above.

The film-forming coagulating materials typically comprise between about15 to about 80% by weight, more typically between about 50 to about 80%by weight, and preferably between about 60 to about 80% by weight of theflavor-bearing sheet.

The flavor-bearing sheets comprise a flavorant. While it is contemplatedthat any flavorant will be useful, the advantages of the presentinvention will be most fully realized where the flavorant is a volatileflavorant. As used herein, the term “volatile flavorant” is intended torefer expansively to any flavorant which readily enters the gas phasethrough evaporation or sublimation at ambient temperatures. Thus, theterm “volatile flavorant” is meant to specifically include, in additionto volatile oils, flavorants which are solid at room temperature butreadily sublime, including for example menthol, camphor, vanillin andthe like. Volatile flavorants suitable for flavoring tobacco smoke arewell known in the art and include, without limitation, acetaldehyde,amyl acetate, anethole, anisole, benzaldehyde, benzylformate,2,3-butanedione, butyraldehyde, camphor, 1-carvone, d-carvone,cinnamaldehyde, citral, citronellol, p-cresyl methyl ether, cymene,dihydrocarvone, dihydrocarveol, 2,4-dimethylacetophenone, dipropylketone, ethyl acetate, ethyl amyl ketone, ethylbutyrate, ethyl butylketone, ethyl valerate, ethyl vanillin, eucalyptol, eugenol, hexenal,geraniol, isoamyl isovalerate, limonene, linalool, menthol, menthone,4-methyl benzaldehyde, methyl ethyl ketone, methyl hexyl ketone, methylsalicylate, 3-methyl valeric acid, pinene, d-piperitone,propylisobutyrate, pulegone, santalol, thujone, vanillin, zingerone andthe like. Menthol is the preferred volatile flavorant.

The volatile flavorant will typically comprise between about 10 to about75% by weight, more typically between about 15 to about 50% by weight,and preferably between about 20 to about 30% by weight of theflavor-bearing sheet.

Illustrative flavor-bearing sheet compositions include withoutlimitation:

-   -   a. polyethylene glycol (about 70 weight %); menthol (about 30        weight %)    -   b. polylactic acid (about 70 weight %); menthol (about 30 weight        %)    -   c. sorbitol (about 79 weight %); menthol (about 20 weight %);        sodium dodecylsulfate (about 1 weight %)    -   d. hydrogenated starch hydrolysate (about 69 weight %); menthol        (about 30 weight %); propylene glycol alginate (about 1 weight        %)    -   e. sodium carboxymethyl cellulose (about 69 weight %); menthol        (about 30 weight %); sodium dodecylsulfate (about 1 weight %).

In addition to the volatile flavorant, the flavor-bearing sheets mayoptionally contain one or more nonvolatile flavorants. Such flavorantsare well-known in the art and include, for example, cocoa, licorice,powdered tobacco, tobacco extract and the like. Volatile flavorantsstabilized in microcapsules may also be present in the flavor sheets.

The flavor-bearing sheets may optionally comprise various additives suchas fillers, emulsifiers, humectants, fragrances, colorants, burn ratemodifiers and the like. In one interesting embodiment, theflavor-bearing sheets comprise an adsorbent material for removing gasphase components of mainstream smoke. Suitable adsorbent materials aredescribed elsewhere herein.

The flavor-bearing sheets may be prepared from solutions or emulsionscomprising the film-forming coagulating material, volatile flavorants,and a solvent. The solvent is typically a protic solvent such as water,ethanol, glycerin, and combinations thereof. The film-formingcoagulating material and volatile flavorants may be added to the solventin any order. It is desirable to apply efficient stirring or agitationto achieve a homogenous solution or emulsion. Stirring may beaccomplished with any conventional mixer, including vertical mixers,planetary mixers, high-shear mixers and the like. Heating may optionallybe employed to increase the solubility or dispersibility of poorlymiscible components. Temperatures of about 40 to about 60° C., andpreferably about 50° C. have been found suitable for this purpose. Itmay be useful to employ an emulsifier to improve the stability ofresultant emulsions.

The mixtures are cast onto a substantially flat surface, such as a glasssheet, stainless steel belt or polystyrene block, to form a layertypically having a thickness of about 0.5 mm to about 3 mm, andpreferably from about 0.5 mm to about 1.0 mm. It has been founddesirable to employ a casting blade for this purpose. Solvent is removedby evaporation under ambient conditions to produce a dried sheet of thenon-volatile vitreous matrix material having the volatile flavorantdispersed therein. Drying times will depend on the selection of solventand drying method. For example ambient drying will typically range fromabout 8 hours to about 24 hours and force warm air drying (e.g.,infrared lamp) will typically range from 5 to 45 minutes.

The flavor-bearing sheets formed from the layer of the menthol mixturehave a thickness typically ranging from about 2 mil to about 5 mil. Itwill be understood that the final moisture content of the flavor-bearingsheet will depend on the thickness of the flavor-bearing sheet as wellas the atmospheric humidity. For example, a flavor-bearing sheet havinga thickness of 5 mil may have a moisture content of 15%±5% and aflavor-bearing sheet having a thickness of 3 mil may have a moisturecontent of 10%±2%.

b. Smokable Materials

In one aspect of the invention, smokable materials are provided byshredding the flavor-bearing sheets described herein and mixing withshredded tobacco filler. The flavor-bearing sheets may be shredded witha paper shredder or the like to produce a plurality of shreddedflavor-bearing sheets. The precise dimensions of the shreddedflavor-bearing sheets are not critical. A confetti cut of about 1/32″ byabout 7/16″ has been found to be useful. However, any other dimensions,such as, for example, a square cut of about 1/32″ by about 1/32″, arealso within the scope of the invention.

Alternatively, the flavor-bearing sheets may be pulverized to provide apowdered composition which can be added to shredded tobacco filler inessentially the same manner. In practice, it has been found lessdesirable to provide the compositions in the form of a powder due to theincrease in total surface area from which menthol may migrate.

The shredded flavor-bearing sheets are mixed with tobacco filler usingany conventional method, including, by way of example, tumbling in arotating drum mixer. The weight ratio of shredded flavor-bearing sheetsto tobacco filler will typically range from about 1:100 to about 1:5depending on the desired level of menthol delivery. Preferably, theweight ratio of shredded flavor-bearing sheets to tobacco filler will befrom about 1:10 to 1:20.

Any shredded tobacco may be used with the present invention. Examples ofsuitable tobaccos include, but are not limited to, flue-cured, Burley,Turkish, Oriental, expanded tobacco, and reconstituted tobacco. Othertobacco materials suitable for use in the present invention aredescribed in U.S. Pat. No. 5,404,890 to Gentry et. al., the disclosureof which is hereby incorporated by reference. A preferred tobacco is lowtobacco-specific nitrosoamine (low TSNA) tobacco. The tobacco may betreated with additives and the like according to conventional practice.

c. Flavored Cigarettes

In another aspect of the invention, flavored cigarettes are provided.Flavored cigarettes according to the invention typically comprise apaper-wrapped cylindrical column of tobacco. The tobacco columncomprises shredded flavor-bearing sheets in admixture with cut tobaccofiller, as described above.

It is contemplated that the present invention may be applicable tocigarettes having filters, as well as cigarettes without filters. Withregard to cigarettes having filters, the filter may be attached at themouth or buccal end of the tobacco column. The filter may be attached tothe tobacco column using any method known in the art, such as aconventional tipping overwrap.

The filter may be any of various types of filters suitable forcigarettes. For example, the filter may comprises a plug (i.e., “tow”)of filter medium capable of removing particulate material frommainstream smoke. The filter plug may comprise fibrous, webbed, andcorrugated materials, formed from polyolefins, polyesters, cellulosicsand the like. Cellulosics may include paper and cellulose acetate fiber.While such filters are effective for removing particulate material suchas tar from mainstream smoke, they are ineffective for removing orreducing gas phase constituents of mainstream smoke. Therefore,preferred filters will incorporate an adsorbent material, such asactivated carbon or Sepiolite, in a section of the filter.

As used herein, the term “adsorbent” is intended to have its ordinaryand accustomed meaning in the art, but should not be construed aslimiting the invention to any particular mechanism or mode of action bywhich gas-phase constituents in mainstream smoke are reduced. Forinstance, in accordance with the ordinary and accustomed nomenclature inthe art, activated carbon and Sepiolite are referred to herein as an“adsorbents,” but carbons and minerals which reduce gas phaseconstituents by adsorption, absorption, chemisorption, or otherwise arecontemplated as being within the scope of the invention.

Suitable adsorbent materials for use in the filters of the presentinvention include, but are not limited to, activated carbon, zeolite,magnesium silicates, aluminum silicates, silica gel, meerschaum,aluminum oxide, and florisil. Synthetic adsorbents such as, for example,carbonaceous resins derived from the pyrolysis of sulfonatedstyrene-divinylbenzene and sold under the trademarks Ambersorb 572 orAmbersorb 563 (Rohm and Haas, 5000 Richmond Street, Philadelphia, Pa.19137) may also be employed.

Activated carbon adsorbents are preferred. Any activated carbon materialmay be used in the practice of the invention, including but not limitedto carbon materials derived from coal, tobacco material, peat, woodpulp, coconut hulls, kapok fibers, cotton fibers, cotton linters, andthe like. Activated carbon materials of any degree of activation(surface area) may be used according to the present invention.Preferably, the activated carbon materials will have a degree ofactivation so as to provide about 25 to about 125 weight percent pickupof carbon tetrachloride. More preferably, the activated carbon materialwill provide about 60 weight percent pickup of carbon tetrachloride. Anymesh size activated carbon is useful in the practice of the invention.However, larger mesh size activated carbons may provide advantagesduring the manufacture of the cigarette, particularly in thoseembodiments of the invention having a filter cavity which is chargedwith a bed of activated carbon. Preferred activated carbons are granularcoconut carbons with a mesh size of about 18×40 U.S such as coconut hullbased carbons available from Calgon Corp. as PCB, PCGB and GRC-11 andthose available from PICA USA (Columbus, Ohio) as G278.

Certain minerals are also preferred adsorbents in the practice of theinvention. Suitable minerals include, for example, the hydratedmagnesium silicate Sepiolite (TOLSA, S.A.) and the hydrated aluminumsilicate Attapulgite (TOLSA, S.A.). Sepiolite and Attapulgite belong tothe palygorskite family of minerals. They are lightweight, porous clayshaving a large specific surface and low chemical activity.

In one embodiment, the filter comprises a so-called “dalmation” filtercomponent. A dalmation component comprises a fibrous filter material,such as cellulose acetate, which has been impregnated with an adsorbent.Typically, the fibrous filter material is treated with a plasticizer,such as triacetin, followed by dispersion of the adsorbent particlesinto the fibrous material. Dalmation filter components, and their methodof manufacture, are well known in the art as described in U.S. Pat. Nos.6,257,242 B1 (Stpyridis), 5,622,190 (Arterbery et al.), 5,568,819(Gentry et al.), 3,101,723 (Seligman et al.), the disclosures of whichare hereby incorporated by reference.

It is also known to incorporate adsorbents, such as activated carbon,into paper filter components. Accordingly, the filter may be providedas, for example, a cellulose acetate tow having a carbonaceous papergathered within the tow or wrapped concentrically around the tow, asdescribed in U.S. Pat. No. 5,568,819 (Gentry et al.), the contents ofwhich are hereby incorporated by reference.

In another embodiment, the filter is provided in a so-called“plug-space-plug” configuration. In this embodiment, the filter willcomprise a first particulate filter component at the buccal end of thefilter and a second particulate filter component abutting the tobaccorod. The particulate filter components may be formed from any materialsuitable for removing particulates from mainstream smoke, as describedabove. The first and second particulate filter components are spacedapart to form a filter cavity therebetween. The filter including allthree components is circumscribed by a conventional paper wrapper. Thefilter cavity will contain a bed of filter material comprising a gasphase adsorbent, such as granular activated carbon. The cavity ispreferably filled to a 90% full condition, and more preferably to atleast a 95% full condition, with the adsorbent filter medium. The amountof adsorbent should be selected to achieve the most effective gas phasereduction within the limits of the smoking article. Preferably, thecavity is filled with about 125 mg to about 150 mg of activated carbon.In one interesting embodiment, the cavity is charged with activatedcarbon and Sepiolite in weight ratio ranging from 0:100 to 100:0.

The cigarettes of the invention are not limited to any dimension.Typical cigarettes are cylindrically shaped rods having circumferencesof about 22 mm to about 25 mm. The cigarette may be any length,including but not limited to, 80 mm, 84 mm, and 99 mm. In a preferredembodiment, the cigarette is 84 mm long and the downstream tow is 10 mmin length. The cavity ranges from about 3 mm to about 8 mm in length,and is preferably between about 5 mm and about 6 mm in length. In anembodiment where the cavity is 5 mm in length, the upstream tow is 10 mmin length. In another embodiment, the cavity is 6 mm in length and theupstream tow is 9 mm in length.

In another preferred embodiment, the cigarette is 99 mm long and thedownstream tow is 10 mm in length. The cavity ranges from about 3 mm toabout 8 mm in length, and is preferably between about 5 mm and about 6mm in length. In an embodiment where the cavity is 5 mm in length, theupstream tow is 12 mm in length. In another embodiment, the cavity is 6mm in length and the upstream tow is 11 mm in length.

Ventilation may be provided by one or more circumferential rows ofperforations through the tipping paper. The perforations may be locatedbetween the upstream and downstream ends of the filter cavity containingthe adsorbent. Ventilation is preferably provided in the filter cavityby perforations located 14.5 mm from the buccal end of the downstreamtow. As is well-known, ventilation reduces the amount of mainstreamsmoke reaching the smoker through dilution by ambient air and also tendsto increase filtration efficiency by decreasing the velocity ofmainstream smoke upstream of the perforations and thereby increasing itsresidence time in the filter.

Examples of commercially available adsorbent filters include Caviflex,Dualcoal, Recessed Dualcoal, Sel-X-4, and Triple Filter from BaumartnerFibertec (Switzerland); Active Acetate Dual, Active Charcoal TripleSolid, Active Myria White, Active Patch Mono, Adsorbent Coated Thread,Triple Granular, and V.P.A. Dual from Filtrona InternationalIncorporated (Milton Keynes, U.K.), each of which are contemplated to beuseful in the practice of the invention.

The wrapping papers and tipping papers used in the practice of theinvention may be any of the papers known in the art, includinglow-sidestream paper and reduced ignition propensity paper such as thosedisclosed in U.S. Pat. No. 6,837,248 to Zawadzki et al., which is herebyincorporated by reference.

The present invention is not limited to the filter designs describedabove. It is contemplated that other filter arrangements are suitablefor use with the present invention, including but not limited to thosedescribed in European Patent Application No. 579,410 and U.S. Pat. Nos.5,568,819 (Gentry et al.), 5,365,951 (Arterbery et al.), 5,067,499(Banerjee et al.), 4,881,556 (Clearman et al.), 4,357,950 (Berger etal.), 3,894,545 (Crellin et al.), which are hereby incorporated byreference. It will be appreciated by one skilled in the art that certainmodifications and variations of the above described embodiments arewithin the scope of the invention.

The following non-limiting examples are provided to illustrate variousembodiments and attributes of the present invention. Examples 1-4demonstrate various embodiments of the flavor bearing sheet of thepresent invention.

EXAMPLE 1

A flavor-bearing sheet according to the present invention is provided bymixing 100 g of carboxymethyl cellulose with 900 g of water using anelectric overhead stirrer to yield a 10% by weight aqueous carboxymethylcellulose solution. To the solution was added 100 mg of sodiumdodecylsulfate and the mixture was warmed to 50° C. 25 g of menthol wasadded and the mixture was stirred until the menthol was melted andhomogenously dispersed into the solution. The mixture was allowed tocool to room temperature with continued stirring. The mixture was thencast onto polystyrene blocks using a casting blade set to 1.5 mmthickness and dried overnight under ambient conditions. The resultantsheet was separated from the polystyrene block and shredded to aconfetti cut of about 1/32″ by about 7/16″ with a paper shredder.

EXAMPLE 2

Another embodiment of a flavor-bearing sheet of the present invention isprovided by slowly adding 11 g of carboxymethyl cellulose to a mixtureof 190 g of water, 1 g of insoluble cellulose, and 0.5 g of caramelcoloring. The mixture was continuously stirred at 500-1000 rpm for about30 minutes until the carboxymethyl cellulose dissolved resulting in abrown opaque viscous mixture without lumps.

Separately, a menthol solution consisting of 9.5 g of propylene glycol,2.4 g of glycerol, 11.9 g of menthol, and 0.09 g of polysorbate 80 werestirred together until dissolved. The opaque viscous carboxymetholcellulose mixture was placed in a warm water bath at about 50° C. andthe menthol solution was added. The mixture was stirred at 500-1000 rpmuntil creamy (about 15 minutes). The mixture was cast onto glass platescoated with cooking spray at 1.0 mm thickness and dried in oven at 90°C. for 45 minutes.

EXAMPLE 3

A further embodiment of a flavor bearing sheet of the present inventionis provided by stirring 1 g of an insoluble cellulose with 112 g ofwater at 300 rpm for 10 minutes. 11 g of pectin powder was then stirredinto the mixture before it was heated to 185° F. The pectin mixture wasremoved from the heat and the viscous liquid was allowed to cool to roomtemperature with stirring.

Separately, a menthol mixture consisting of 7.2 g of propylene glycol,1.8 g of glycerol, 9 g of menthol, and 0.13 g of polysorbate 80 wasstirred together until dissolved. The menthol solution was stirred intothe pectin mixture at 500 rpm in a warm water bath at 50° C. for 20minutes. The mixture was cast onto glass plates coated with cookingspray at 1.0 mm thickness and dried in oven at 90° C. for 45 minutes.

EXAMPLE 4

In another embodiment of the a flavor bearing sheet of the presentinvention 5 g of sodium alginate and 2 g of Gum Arabic were sprinkledinto a stirred solution of 95 g of water and 4 g of propylene glycol andstirred until the solids dissolved. 4 g of solid menthol and 0.35 g ofsodium dodecylsulfate were added and stirred into the mixture in a warmwater bath at 50° C. for 20 minutes. The mixture was cast onto glassplates coated with cooking spray at 1.0 mm thickness and dried in ovenat 90° C. for 30 minutes.

The following example demonstrates the improvement in film quality ofthe flavor bearing sheet of the present invention by adding propyleneglycol.

EXAMPLE 5

Five flavor bearing sheets were prepared having the ratio of ingredientsas set forth in the following table. In each of these sheets 0.10 g ofsodium dodecylsulfate was used as the emulsifier and the sheets weredried under an infrared lamp.

Propylene Carboxymethyl Sample Glycol Menthol Cellulose Sheet 1:  5% 30%65% Sheet 2: 15% 30% 55% Sheet 3: 25% 30% 45% Sheet 4: 35% 30% 35% Sheet5: 45% 30% 25%

Sheet 1 exhibited visible streaks of crystallized menthol in thefinished sheet and on the surface while Sheet 2 had less. Sheets 3, 4,and 5 exhibited no evidence of crystallized menthol in the sheets.

The following example demonstrates the improvement in film quality ofthe flavor bearing sheet of the present invention by adding glycerol,and the improvement in the taste quality of cigarettes made with suchflavor bearing sheet.

EXAMPLE 6

Flavor bearing sheet 1 was prepared by dissolving 12 g of carboxymethylcellulose into a solution of 108 g of water and 9 g of propylene glycol.When the carboxymethyl cellulose was dissolved (after about 30 minutes),the mixture was stirred in a warm water bath where 9 g of solid mentholand 0.1 g of sodium dodecysulfate were added to the mixture. The mixturewas stirred about 15 minutes until the menthol melted to yield a creamymixture. The mixture was cast onto a polystyrene plate at 1.0 mmthickness and dried under an infrared lamp for 30 minutes, thenair-dried until dry to the touch.

Flavor bearing sheet 2 was prepared by dissolving 12 g of carboxymethylcellulose into a solution of 108 g of water, 6 g of propylene glycol,and 3 g of glycerol. When the carboxymethyl cellulose was dissolved(after about 30 minutes), the mixture was stirred in a warm water bathwhere 9 g of solid menthol and 0.1 g of sodium dodecysulfate were addedto the mixture. The mixture was stirred about 15 minutes until thementhol melted to yield a creamy mixture. The mixture was cast onto apolystyrene plate at 1.0 mm thickness and dried under an infrared lampfor 30 minutes, then air-dried until dry to the touch. It was observedthat flavor bearing sheet 2 was more flexible than flavor bearing sheet1.

The prepared flavor bearing sheets were cut and blended with tobacco tomake cigarettes. Three out of four panelists preferred the taste ofcigarettes having flavor bearing sheet 2 containing glycerol compared tothe taste of cigarettes having flavor bearing sheet 1.

Examples 7-9 provide stability studies of various embodiments of flavorbearing sheets of the present invention described in the Examples aboveto evaluate their ability to retain menthol when exposed to atmosphericconditions.

EXAMPLE 7

Samples of shredded flavor bearing sheets of Example 1 were weighed intovials and left open to ambient conditions for 14 days. Control samplesof mentholated tobacco prepared by spraying tobacco with an ethanolicsolution of menthol were similarly weighed into open vials. The controlsamples were obtained from freshly prepared Newport® brand cigarettes.Menthol content of the shredded flavor bearing sheet samples and controlsamples was determined by measuring weight loss after 1, 2, 3, 4, 7, and14 days exposure to ambient conditions. The results are plotted in FIG.1 as the percentage loss of menthol based on the initial weight.

As illustrated in FIG. 1, about 20% of the menthol was lost from theshredded flavor-bearing sheets over the first day followed by a rapidstabilization in menthol loss. Without wishing to be bound by anytheory, it is believed that the initial menthol loss might be explainedby the migration of loosely encapsulated menthol at or near the surfaceor the sheet. After loss of loosely encapsulated menthol over the firstday, only about 10% additional menthol is lost over the next 13 days,with a total menthol loss after 14 days of about 25%. In the controlsamples, a very slight increase in weight was observed over the firstthree days. It is believed that this effect may arise due to thehydroscopic nature of dried tobacco which allows it to absorb water fromthe air, thereby preventing the menthol loss to be accurately measureduntil the tobacco moisture levels establish equilibrium with ambientwater over the first three days. Thereafter, the weight loss in thecontrol samples rapidly accelerates to yield a total weight loss ofabout 50% after 14 days.

EXAMPLE 8

Flavor bearing sheets as prepared in Examples 5 and 6 were shredded.Twenty samples of each flavor bearing sheet were weighed into vials (40mg each) and left open to allow menthol to evaporate. Mentholatedtobacco from a commercial product was likewise weighed into 20 vials.Three vials from each sample were extracted and evaluated for mentholcontent weekly for 4 weeks. As shown in FIG. 2, the mentholated sheetsshowed superior retention of menthol when compared to conventionalmentholated tobacco.

EXAMPLE 9

This example demonstrates the improvement in the retention of menthol inthe flavor bearing sheet by using an infrared lamp to quickly dry theflavor bearing sheet before separation of a hydrophobic flavor from theaqueous medium.

In this example, a flavor bearing sheet according to the presentinvention was prepared by slowly admixing 22.5 g of carboxymethylcellulose to a solution of 0.9 g of propylene glycol, 0.1 g of sodiumdodecylsulfate (0.1 g), and 150 g of water stirred at 500 rpm. Themixture was stirred an additional 30 minutes until the carboxymethylcellulose dissolved to yield a clear viscous liquid. The mixture wasplaced in a warm water bath at 50° C. while 7.5 g of solid menthol wasadded. The mixture was stirred warm for 15 minutes at which time thementhol had completely dispersed into a creamy emulsion.

About one-half of the mixture was cast onto a polystyrene plate at 0.75mm thickness and allowed to dry ambiently overnight. The resulting sheethad a rough texture on the top surface with a noticable amount ofcrystalline menthol on the surface of the film.

The other half of the mixture was cast onto a polystyrene plate at 0.75mm thickness and dried under an infrared lamp to speed the drying of thefilm. The resulting sheet was smooth on both surfaces and had verylittle evidence of crystalline menthol at the surface.

As shown in FIG. 3, the flavor sheet sample that was dried quickly bythe infrared lamp proved to be superior compared to the air dried flavorsheet sample with regard to the retention of menthol over a 4 weekperiod.

Examples 10 and 11 provide stability studies of menthol in a shreddedflavor bearing sheet included in the tobacco rod of a cigarette.

EXAMPLE 10

A smokable composition was prepared by mixing 2.20 pounds of theshredded flavor-bearing sheets of Example 1 with 25.0 pounds of cuttobacco for four revolutions in a rotating drum. Cigarettes havingplug-space-plug filters were prepared with the resultant mixture. Thecigarette filters had a 10 mm plug of fiber tow at the buccal end, a 9mm plug of fiber tow at the upstream end and a 6 mm cavity charged with150 mg of sepiolite granules. The mean menthol content of each cigarettewas 7.52 mg with a Relative Standard Deviation of 10.0%. As shown inFIG. 4, after 47 weeks in a sealed package, the menthol levels in themainstream smoke of the cigarettes was greater than 70% of the initialvalue.

FIG. 5 shows a comparison of the menthol levels in the mainstream smokeof the cigarettes of Example 10 having shredded menthol sheets of thepresent invention prepared according to Example 1 and conventionalcarbon filter cigarettes having mentholated tobacco prepared by sprayingtobacco with an ethanolic solution of menthol. As illustrated in FIG. 5,after about 10 weeks in sealed packs, the menthol levels in themainstream smoke of the cigarettes having the shredded mentholatedsheets is superior to that of the conventional cigarettes having theethanolic menthol solution sprayed on the tobacco.

EXAMPLE 11

A flavor bearing sheet according to the present invention is provided bydissolving 48 g of carboxymethyl cellulose in a solution of 3.6 gpropylene glycol and 352 g water with mechanical stirring. 20.5 g ofsolid menthol was added to the viscous liquid and the mixture wasstirred in a warm water bath until all of the menthol had melted. 0.4 gof sodium dodecylsulfate was added and the mixture was stirredvigorously at 800 rpm for 1 minute. The warm water bath was exchangedfor a cool water bath and the mixture was stirred for 10 minutes tobring the mixture to room temperature. The mixture was cast ontoPTFE-coated glass plates at a thickness of 1.0 mm and dried under aninfrared lamp for 30 minutes. The sheets were then placed under a fanuntil dry to the touch, and shredded to 1/32″× 7/16″ strips using apaper shredder. In this manner, 3500 g of the mentholated sheet wasprepared.

The shredded sheet was loaded into a metered solids addition funnel andthe discharge was directed into the tobacco flow of a cigarette maker.The mentholated sheet was added at 60.0 g/min while the maker speed wasset to 1100 cig/min to give an average content of 54 mg sheet percigarette. The cigarettes were packed and evaluated weekly for mentholdelivery. The menthol delivery in the mainstream smoke is plotted inFIG. 6. In addition, the cigarettes were evaluated monthly for taste. Asshown in FIG. 7, the menthol taste intensity of the cigarettes wasdeemed to be acceptable for at least six months after packaging.

Certain modifications and improvements will occur to those skilled inthe art upon a reading of the foregoing description. It should beunderstood that all such modifications and improvements have beendeleted herein for the sake of conciseness and readability but areproperly within the scope of the following claims.

1. A flavor-bearing sheet for the controlled delivery of volatileflavorants in a smoking article, said flavor-bearing sheet comprising anon-volatile vitreous matrix having one or more volatile flavorantsdispersed therein, said non-volatile matrix comprising a film-formingcoagulating material; wherein said film-forming coagulating materialcomprises between about 15 to about 80% by weight of said flavor-bearingsheet and said one or more volatile flavorants comprise between about 20to about 75% by weight of said flavor-bearing sheet.
 2. Theflavor-bearing sheet of claim 1 wherein said film-forming coagulatingmaterial comprises a material selected from the group consisting ofpolyols, polymeric ethers, polymeric esters, natural polymers andderivatives thereof, and combinations thereof.
 3. The flavor-bearingsheet of claim 2 wherein said polyol is selected from the groupconsisting of erythritol, glycerol, isomalt, mannitol, sorbitol,xylitol, maltitol, lactitol, inositol, hydrogenated starch hydrolysate,dextrose, glucose, fructose, sucrose, maltose, galactose, lactose, cornsyrup and combinations thereof.
 4. The flavor-bearing sheet of claim 2wherein said film-forming coagulating material comprises a polymericether selected from the group consisting of polyethylene glycol (PEG),polypropylene glycol (PPG), PEG/PPG copolymers, alkoxylated alcohols andcombinations thereof.
 5. The flavor-bearing sheet of claim 2 whereinsaid film-forming coagulating material comprises a polymeric esterselected from the group consisting of polylactic acid (PLA),poly-3-hydroxybutyrate (PHB), polyglycolide, polycaprolactone (PCL), andcombinations thereof.
 6. The flavor-bearing sheet of claim 2 whereinsaid film-forming coagulating material comprises a natural polymer ornatural polymer derivative selected from the group consisting ofcellulose, ethyl cellulose, methyl cellulose, hydroxypropyl cellulose,carboxymethyl cellulose, hydroxypropyl alginate, and combinationsthereof.
 7. The flavor-bearing sheet of claim 1 further comprising anemulsifier.
 8. The flavor-bearing sheet of claim 1 wherein said one ormore volatile flavorants comprises menthol.
 9. The flavor-bearing sheetof claim 8 wherein the loss of menthol upon storage in ambientconditions for 100 days is less than about 25% by weight based on theinitial weight of menthol.
 10. A smokable composition comprising aplurality of flavor-bearing sheets according to claim 1 dispersed inshredded tobacco filler.
 11. A cigarette comprising a tobacco column,said tobacco column comprising the smokable composition of claim
 10. 12.The cigarette of claim 11 further comprising a filter abutting saidtobacco column, wherein said filter comprises an adsorbent materialwhich reduces at least one gas phase constituent of mainstream smoke.13. The cigarette of claim 12 wherein said adsorbent material comprisesactivated carbon.
 14. The cigarette of claim 12 wherein said filtercomprises: (i) an upstream fibrous filter component and a downstreamfibrous filter component, said upstream and downstream fibrous filtercomponents defining a filter cavity therebetween; and (ii) a filtermaterial disposed in said filter cavity, said filter material comprisingan adsorbent material which reduces at least one gas phase constituentof mainstream smoke.
 15. The cigarette of claim 12 wherein said filtercomprises a fibrous filter component having an adsorbent material whichreduces at least one gas phase constituent of mainstream smoke dispersedtherein.
 16. The cigarette of either claim 14 or 15 wherein saidadsorbent material comprises activated carbon.
 17. A cigarettecomprising: (a) a tobacco column including a smokable materialcomprising: (i) shredded tobacco filler; and (ii) a plurality offlavor-bearing sheets in admixture with said tobacco filler, saidflavor-bearing sheets comprising a non-volatile vitreous matrix havingmenthol dispersed therein, said non-volatile matrix comprising afilm-forming coagulating material selected from the group consisting ofpolyols, polymeric ethers, polymeric esters, natural polymers andderivatives thereof, and combinations thereof; wherein said menthol isreleased into the mainstream smoke upon combustion of said smokablematerial.
 18. The cigarette of claim 17 further comprising a filterabutting said tobacco column, wherein the filter comprises an adsorbentmaterial.
 19. The cigarette of claim 18 wherein said adsorbent materialcomprises activated carbon.
 20. The cigarette of claim 17 wherein themainstream smoke menthol delivery of said cigarette is greater thanabout 70% of its initial value after storage for about 25 weeks in asealed cigarette package.